1. Field of the Invention
This invention relates to a method of and apparatus for making refractory articles. More particularly, the invention relates to a method of and apparatus for making carbon fiber reinforced composite components for thrust nozzles of rocket motors.
2. Description of the Prior Art
Solid propellant rocket motors produce gases under high pressure having temperatures of the order of about 6,000.degree. F. These gases contain both erosive and corrosive combustion products. The combustion products pass through the nozzle throat at sonic velocities and through the exit cone at supersonic velocities. The exhaust gases impinge upon the surfaces of the thrust nozzle with the full impact of the heat, erosiveness, and pressure almost immediately upon ignition of the rocket motor. As a consequence, the materials of the nozzle and of the throat, especially, must be capable of withstanding such a severe environment.
Early nozzle throats for solid propellant rocket motors were made of forged tungsten. These functioned satisfactorily for their intended purposes. They were, however, expensive, excessively heavy, and difficult to make. Later nozzle throats have been made with graphite and exit cones have been made of high-temperature plastic composites, wherein, strong, high-temperature resistant fibers are filled with a thermosetting resin. Exit cones are also commonly made of high-temperature resistant cloth impregnated with a resin and formed into the desired shapes under high temperatures and pressures. Such nozzles are satisfactory for use with rocket motors designed prior to about 1980 or rocket motors that operate at relatively cool temperatures. When used in the latest, high-performance rocket motors having propellants that burn at much higher temperatures, however, such nozzles tend to separate or delaminate into the layers of material with which they are formed. As a result, carbon-carbon composites have found application for nozzle manufacture. These materials, however, are costly from a material and labor standpoint, requiring a great deal of hand labor. In-process rejections have also been great, adding to the total unit cost of the nozzles.
There thus exists a need and a demand for an improvement in the methods of and apparatus for making refractory articles, and in particular, nozzles having utility in high-performance rocket motors, of composite materials that are of lower cost from both the material and labor standpoints than those of the prior art.